Grinding & Classification Circuits

Grinding & Classification Circuits

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Geared and gearless Drives of Tumbling Mills (1 reply)

2 years ago
Dachmann 2 years ago


I was told in this forum that economic efficiency is one of the major reasons for the ongoing popularity of Tumbling Mills in mineral processing. Concerning my questions I need some insight of experts with practical experience.

Looking at SAG mills for instance there are huge differences in CAPEX regarding their different drive systems. Especially in the the multi-MW class gearless drive systems seem to be a thing because of their advantages such as variable speed control and low maintenance requirements. How much of the total costs of a SAG mill relate to the drive system?

I wonder why geared drive systems are popular in the lower MW class but lose on relevance with increasing power, even though there are geared solutions rated up to 32MW (Metso QdX4). What are the practical reasons behind this? I mean, at least some lower developed countries could have invested in a geared system to save a decent amount of money. 

I assume that maintenance is a major factor since the large ring gear is exposed to dirt and high forces. Why then, did'nt other gear designs come into favor such as seen here:

Please give me detailed info as why you think this is not a practical solution.


Thank you very much for your insight.




1 year ago
David 1 year ago

A case by case trade off is to be done. Farnell Thomson Montreal based could do this. Here is a paper you will find useful.

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